Reclinable chair

A reclinable chair comprising:

• a seat frame;
• a backrest frame pivoted to a rear side of said seat frame;
• two armrest units, at least one of which includes a sleeve, and a core rod that extends through said sleeve, that is movable in a front-rear direction relative to said sleeve and that has a rear end pivoted to said backrest frame, said sleeve including a tubular body surrounding said core rod and having an inner peripheral surface that defines a passage, said core rod extending through said passage and being spaced from said inner peripheral surface by an annular gap, said tubular body further having a through hole communicating with said passage, said at least one of said armrest units further including a biasing member disposed between a front end of said tubular body and a front end of said core rod;
• and
• a positioning member disposed in said sleeve and including an engaging portion disposed around said core rod and within said annular gap, said engaging portion including two curved sections, and an intermediate section connected between said curved sections, said engaging portion having a thickness that increases gradually from said curved sections to said intermediate section, said intermediate section protruding partially into said through hole, said curved sections extending from said intermediate section in two opposite directions away from said through hole into said annular gap, said intermediate section having a thickness larger than a width of said annular gap, said positioning member being movable between a loose position, where said intermediate section is not squeezed into said annular gap, and a tight position, where said intermediate section is squeezed tightly into said annular gap to thereby restrict movement of said core rod relative to said tubular body;
• wherein, when said backrest frame is reclined to pivot rearward relative to said seat frame, said core rod of said at least one of said armrest units is driven to move rearward relative to said tubular body so that said biasing member is compressed to store a restoring force which biases said backrest frame to pivot forward, thereby stabilizing said backrest frame at a reclining angle.